Sometimes I wish ALGORE hadn't invented it.

Kelly, thanks for setting the record straight.

If an individual has to use the word "qualified" in an internet handle it does lead me to question their qualifications. Your shop, on the other hand, has a well known reputation for high quality work.

As well, Union Pacific has been tarred with the same brush, as they were accused of using these (allegedly) substandard wheelsets. I believe they, too, have a reputation for quality work.



These photos should be very easily obtained by anybody with access to 844, either in the shop or on the road when the engine is at rest. Frankly, I doubt you'll see any such defects if/ when photos surface.

Hopefully somebody can post photos showing the newly turned wheels!

It's far too easy to wrongly defame an individual or organization on the internet, particularly when not giving your real name and hiding behind the old "I heard a rumour" line.

"TQE", if you're going to make derogatory statements, then man up, use your real name, and provide the evidence to prove your claim.

Steve Hunter

Friends,

I deleted one post that was outside of the guidelines of the Interchange. If you see a post that falls outside the guidelines feel free to hit the "REPORT" button to quickly bring it to the attention of your moderators.

Thanks,

Tom Gears
Moderator

What is the challenge in these large turnings? Is it the nature of the cross slide on the wheel lathe or does the lathe actually flex this much on such large scale? Is it hard to get the tool to bite into the tire?

I have little doubt of the quality of the work by either shop. As the man says, put up or shut up.

Steve

Anyone familiar with wheel lathes capable of turning large drivers would know that as large as they are, these machines are capable of precision within a few thousandths of an inch. The ONLY issue is actually handling the wheelsets and getting them set up in the lathe in the first place.

I suspect tool wear is an issue, given the relative hardness of tires and the shear volume of material to be removed. .006" on the diameter is .003" on the cut; I could see the nose of the tool wearing that much in one pass, especially if that pass was a skim cut trying to bring the dimension in a little closer.

Considering the FRA spec. is apparently .09375" on the diameter, and Strasburg gave them .006", I'd say they were doing pretty good.

I'm not quite a machinist, but I've scorched and destroyed a fair share of lathe bits. Back in the olden days, you would have a guy whos job it would be to shape and sharpen and harden the bits. Nowadays, many shops go with the option of a ready-made lathe bit of carbide or another extra-hard material. The angle of a bit edge is probably something like 70-80 degrees (I don't have much experience with making lathe bits only killing them lol), but the edge is RAZOR sharp. Now with that angle, it's hard to cut flesh, but a nice bit is noticeably fine to the skin. Once you've taken off 3 thousands, you're probably 2.9 thousandths overdue to rework or replace the bit. Judging from how much metal I've taken off with a brake lathe with one bit lasting for years, A good machinist with one bit could probably not even have to replace or rework it. In other words, once you're to the point where the bit wear is figuring into the tolerance, you're trying to cut with a blunt piece of metal anyways.

Robert

Robert and others,
Wheel lathe work is not like working on an engine lathe. Once the wheels are set between the centers of the faceplates, and the drive dogs are set, the majority of the material is plowed off with a slug type piece of very tough and hard tool steel at low (2-3RPM) speed. Big ugly and hot chips are produced. The cutting tool does wear and they don't last all that long before heat and abrasion take their toll. Then the running tread diameter is finished, the flange is finished ,and the edge radius is finished, one at a time with specially ground form tools held in a pre-determined position on the turret. The cutting tool for the tread acts more like a scraper as it finishes the running tread surface. The wheel tread is measured with a pi tape at a specific point (with conical wheels) to the desired diameter. Pi tapes are capable of measuring to .001" The flange profile, and the edge radius is machined up to and blended the tread diameter. Flange thickness is tweeked in with a wheel gauge if necessary. The edge radius is blended into the tread diameter. The convenient thing about wheels lathes is that you can work on both wheels at the same time at least for the roughing step. Each turret works independently of the other. Almost like running two separate lathes on one job at the same time. You get one wheel started on it's roughing cut, then start working on the other wheel.
The surface of the machined wheel (at least from an older wheel lathe) is not a mirror finish. It's the running of the wheel on the rails that really polishes the tread and flange.

Bruce's comments and descriptions got me curious about seeing what a wheel lathe actually looks like in action. Of course, some shots are on YouTube, and at least one is at Strasburg:

http://www.youtube.com/watch?v=_kRQ3VhmApM

http://www.youtube.com/watch?v=iF22RyH4 ... re=related

http://www.youtube.com/watch?v=5ulDDQ6x ... ure=relmfu

What looks to be a British lathe on a company called the Tanfield Railway:

http://www.youtube.com/watch?feature=en ... 1JMH4kHORU

The RPM is irrelevant to the work at hand, it's more in the 'surface speed', at 80 inches and 3 RPM that's 12 inches a second of cutting, a smaller peace would be spinning a lot faster to keep up the same cutting speed.
I assume all your bits are custom ground of high speed/tool steel so it's not convenient/economical to work with carbide or some of the other exotic materials that can wear longer. Or can the bits be bought ready made? I would assume you can only buy them ready-to-go if the same ones happen to work on modern rail equipment. And I had no doubt a shop of Strasburg's reputation would -never- let a wheel as crappy as described out the door. If it had to be cut down further a call would of been made to TVRM with the new number. Had a part in an 'interesting discussion' on Trainorders, a lot of folks figured it was insane to ship wheels to two shops because they would never be the same-let me cut and paste some of my posts on it here:

my first reply:
Oh good lord folks, I promise they spent more time brewing coffee then they spent time fretting over getting the wheel diameters identical. The two shops measured, had a quick phone call, had the 'who has the worst wheel' contest, subtracted a bit for a margin of error, wrote the agreed diameter on the work order, and went to cutting. Getting a diameter within the tolerances required for this application is so basic to a machinist that if you can't get it right, you're NOT a machinist at all. Far more work went into setting up the wheels, verifying the centers and runout, measuring the actual damage...not to mention the measuring that went into getting the profiles correct. Then there is cutter bit material, cutting angle, cutting speed, cutting depth....

they still didn't get it so next:
OK...let me try again. I say they did not fret over it NOT because they didn't plan to match them, I say they did not fret because that's what a machinist does! If I call 10 qualified carpenters and ask them to all cut me a 2x4 to exactly 79 7/8ths inches long, I expect them all to be able to do it. First thing an apprentice machinist would to is make a metal bar into a specific diameter. If he proved incapable, with proper training, of getting his plain round bar to specified diameter, he would be lucky if he was allowed to stick around and push broom real machinist's filings out of the way. If I sent 100 wheelsets off to 100 shops with the proper equipment and told them all to cut to proper profile at 79.875 +/- 0.010, I should expect a competent shop to be able to get it done, or tell me I don't have enough metal, or the odd shop out to call up and let me know they screwed up a wheel and it can no longer be trued up to my spec. Not for them to fret over if they even know how to make it meet my spec.

Then they go nuts thinking a tolerance of +/- 0.010 would cause poor thing to fling itself off the rails(some people there seem to think steam locomotive tolerances are measured in microns or something.....) so my next is:
Oh time to pound this iron horse to dust!

0.010 difference in wheel diameter would be:

0.031 inch difference in distance traveled per wheel rev

8107 wheel revolutions required to equal 1 revolution of difference travel total

over 32 miles to make 1 revolution difference

the diameter of the track required would be 3603 feet, over 47 trips around....

And for another monkey to throw at the wrench, how about the wheel grows 0.012 for every 25 degrees in temp. So park poor 844 with the right side in the sun, say those wheels get 50 degrees hotter, and they are .024 bigger!!

someone care to double check my math? I think my ears got blood runnin out from thinnin' to hard


Now I would ask the smart folks here at RYPN this: as I understand it, the flanges are not what keeps the train on the rails, they are only backup for the taper and rail profile which does the real work. When going around a curve, does a wheel pair tend to slip, or does it tend to 'walk' to the side a bit until the 'contact points' have the appropriate diameter to minimize slippage? I understand on a steam locomotive with 4-6-8-10 or more wheels lashed together forever, there will be slippage.

Robert

Looking at the first video, they are using Kennametal Indexable carbide insert toolholders. Good choice.
HSS tool bits wouldn't be a good choice for hogging material. "Back in the day" they probably worked fine.

Strasburg uses a hydraulic tracing head to generate the wheel profile. With this setup, small carbide inserts will work nicely. I use the old turret style tool holders that are original to the wheel lathe that I operate. I use high speed (crucible steel) inserts for hogging and standard high speed for the form tools. I can take off 3/8" off the diameter of the wheel if necessary to get under the hard spots caused by a flat spot. These slug bits work very well at this on the 100" Niles wheel lathe. I can do a standard re-profiling to a set of 63" locomotive wheels in about 5 hours, depending on how much has to come off to regain a good flange. I can re-profile 4 sets of passenger car wheels in a 10 hour day.

Bruce

Indeed "back in the day" the face of the treads were machined with proper HSS forming tools. With the old school hydraulic tracing attachment (essentially a giant key cutter), the ability to use indexable carbide inserts opens a whole new realm of machining. Kennametal or Sandvik make very fine toolholding equipment, each equally painful on your wallet when you get into deep into the manufacturing market. The key to proper roughing and finishing of the tread facing is solely based on the GRADE and SHAPE (TPMT-443 etc.) of insert chosen, and not so much what holds it. In my travels, I've longed to use ceramic inserts for a job such as wheel profiling, however I've steered clear due to the inconsistency of hard/soft spots when re-profiling. Ceramic does extremely well in anything over 35 Rc but as soon as that drops to anything below, there goes your surface finish and subsequently your insert. Grades of carbide that I've used with great success in this area are C-5/6 uncoated and especially Tri-coated (TiN-AlOx-TiN) due the low speed, low feed, high wear characteristic of this style of machining.

My .02
DC

49CFR Part 230 specifies the maximum allowable tolerances, beyond which the equipment is not allowed to operate. Anyone working on a locomotive knows that the closer to zero you can reasonably get the better the locomotive will run when you are finished. However, it must be remembered that in nearly any project with a goal of approaching zero tolerance, 10 percent of the cost is spent achieving the first 90% of the goal. Actually achieving the minimum tolerance costs the remaining 90%. This law of diminishing returns forces us to be practical and set tolerances which will get the job done in the most economical manner. NASA to the contrary.